Originally used for outdoor wear, coatings and membranes add waterproof breathable qualities to fabrics. But, for the fashion segment, they have to be adapted, and the environment also demands that manufacturers change their ways.
“Waterproof breathable”, “Water-resistant”, “Windproof” … in the past 30 years, new terms have entered the textile lexicon. It’s because new technologies have come to stir things up in the outdoor realm, in the form of waterproof breathable fabrics. The idea is to achieve “humidity control” by blocking the rain, but allowing perspiration to escape.
To achieve this, textiles must be rendered waterproof either with a coating or with a laminate membrane. For fine fabrics, coating can maintain the flexibility of the material, whereas membranes risk giving it a crunchier handle. For heavier bases, however, membranes are more suitable because coatings can cause the fabric to stiffen, due to the multiple layers required.
Coatings – Technical Fabrics “Breathable Coating” from PALTEX COMPANY LTD
Waterproof breathable fabrics can be classified in two main groups:
- hydrophobics have micro-pores large enough to release steam, but fine enough to prevent raindrops from entering. They are made with PTFE (polytetrafluoroethylene) or hydrophobic polyurethane.
- hydrophilics have no pores. Instead, they have absorbent micro-channels that drain away perspiration thanks to a pressure effect. They are made with polyester or hydrophilic polyurethane.
Membranes – Technical Fabrics “Lamination” from PALTEX COMPANY LTD
Whatever the process, the proven qualities of waterproof breathables for outdoor garments are envied by the world of fashion. But what works perfectly in the dry cold of mountains, may not do so well in the temperate atmosphere of cities. And, in fact, waterproof breathables can only release perspiration if there is no condensation. If you wear a treated cotton garment next to the skin, your perspiration will be blocked inside. These high-performance materials have to be carefully dosed. Manufacturers have had to adapt their solutions to the urban environment, with more focus on breathability. This can cause some loss of water-resistance but it retains a windbreaker effect that is often sufficient in town.
Meanwhile, the question of the chemical composition of membranes and coatings raises environmental concern. Researchers are working hard to find alternative solutions, and we are seeing more and more labels marked “PFC free” (no perfluorinated compounds) or “Aqueous base” which means that no solvents are used.
WORDS FROM HISTORY
Gore-tex: in 1969, Bob Gore, son of the found of the American company W.L. Gore, discovered a way to make expanded PTFE (polytetrafluoroethylene). That was the start of Gore-Tex, the first microporous membrane.
Ventile: a brand of 100% cotton, waterproof breathable fabric developed in the UK in the 1930s. The construction of the yarn and the structure of the cloth made Ventile fabrics swell slightly in the presence of humidity, which tightened the interstices of the weave, while allowing perspiration to escape by capillarity and natural evaporation. An eco-responsible alternative?
WORDS FROM EXPERTS
Balas, a manufacturer of technical textiles, has found an ecological solution for its waterproof breathable coatings: “Aqueous-base coatings are less polluting but don’t perform as well. Our solvent-base coatings perform well and pollute less, thanks to smoke recovery, and they have obtained the Oeko Tex label.”
Be Mood Microtex Smart Yard, a manufacturer of functional outdoor and fashion textiles, has perfected a system for managing chemical products by applying the 4Sustainability principles and ensuring full traceability of its products.